Can you folks give me some charge weight guidelines for Triple 7 fffg behind a saboted 290 grain bullet? Rifle is a .50 cal. magnum charge capable Knight Revolution inline, with a 28 inch barrel. I have been using three 50 grain equivalent pellets. My formerly good groups with pellets have become erratic and unpredictable. I have been told that pellets may not store well and this could be the problem. Also I weigh all my charges for my centerfire, and intend to do the same with the FFFG powder. What would a 150 grain "equvilent" weigh?